In aluminum fabrication employing comparatively thick (0.5 inch to 4 inches) members it is often desirable and/or necessary to weld such members together. Heretofore, such welding has been done primarily using the well known so-called multipass gas-metal arc process employing numerous weld passes which are time consuming and conducive to interpass weld defects whereby the welding costs are excessive.
One welding technique which has been used to increase productivity is to position the aluminum members which are to be welded substantially flat whereupon higher welding currents may be used and such currents are substantially greater than the currents that could possibly be used if the members were to be positioned other than flat whereby the number of welding passes, problems, and costs associated therewith may be reduced. However, it is not always possible to position members which are to be welded substantially flat and, in many applications the only way that the welding can be done practically is to position the aluminum members substantially vertically with each weld also extending substantially vertically along the vertical members.
Because of the large mass of molten metal produced during vertical welding and the tendency of such molten metal to fall under the influence of gravity, attempts have been made heretofore to achieve vertical so-called electrogas welding using devices such as sliding shoes, or the like, with such sliding shoes serving to retain the molten metal along the weld until its solidification. However, the main problems in using weld metal retaining sliding shoes are that the sliding shoes must be of special construction and thus are comparatively expensive, and it is necessary to use comparatively sophisticated and hence expensive equipment to move the shoes in a controlled manner. Another problem with the use of sliding shoes is that the partially solidified weld is easily torn by the shoes. Still another problem with the use of sliding shoes is that the strength of welds produced using such shoes has been marginal.